External power supply to radio

[gigi]

@ServiceXp said:

@gigi What kind of problems did you have when connected to the Mega's 3.3v pin?

does not transmit the data. sketch hangs after send data

@pete1450 said:

No problem connecting different power supplies, but often finicky components don't like having separate grounds. Connect the ground of everything together and see how it works.

I try tomorrow

I will keep you updated.

I put together a radio rfm12b, a NRF24L01 and a display 128x64

Thank

[RJ_Make]

@gigi Is there anything else connected to the 3.3v pin? If not, have you tried installing a cap (I have to use 47uf) on the radio across Vcc and GND?

[hek]

I had to use a step down from 5V to get stable 3.3v power on the mega.

[gigi]

@hek said:

I had to use a step down from 5V to get stable 3.3v power on the mega.

unfortunately I did not step down to try!!!!

With PC USB Arduino Mega does not start the radio.

the system only works when I put an external power supply to VIN on Arduino Mega.

after 2 or 3 hours arduino crashes!!!

[gigi]

This is the sketch arduino

emon_mysensors.ino

[RJ_Make]

@gigi Wow, that's a lot of "stuff" on that 3.3v rail. I think that's your problem... What kind of current are you pulling on that rail when the radio is transmitting.?

[gigi]

@ServiceXp said:

@gigi Wow, that's a lot of "stuff" on that 3.3v rail. I think that's your problem... What kind of current are you pulling on that rail when the radio is transmitting.?

now I try to put the temperature sensor on the 5 volt

arduino mega limits the current on 3.3v?

I order AMS1117-3.3V,
My idea:
put the step-down input to 5V external power supply and output on 3.3 rail!!! For not use 3.3 v to MEGA

[RJ_Make]

@gigi

Here are some specs.

Summary:
Microcontroller ATmega2560
Operating Voltage 5V
Input Voltage (recommended) 7-12V
Input Voltage (limits) 6-20V
Digital I/O Pins 54 (of which 15 provide PWM output)
Analog Input Pins 16
DC Current per I/O Pin 40 mA
DC Current for 3.3V Pin 50 mA
Flash Memory 256 KB of which 8 KB used by bootloader
SRAM 8 KB
EEPROM 4 KB
Clock Speed 16 MHz

[gigi]

Relay on

Only 3.3 volt

I do not know if I measured correctly, and my instrument is accurate !!!!!

[RJ_Make]

@gigi I just can't believe that the display, rfm12b and NRF24 on the same 3.3v rail is under 50ma,... not too mention the other stuff on it.. You could try disconnecting everything except the NRF24 and see what happens?

I can't even get my NRF24's to work with the shop's listed boost with the Pro Mini attached without a 'massive' capacitor.

[gigi]

@ServiceXp said:

I just can't believe that the display, rfm12b and NRF24 on the same 3.3v rail is under 50ma,... not too mention the other stuff on it.. You could try disconnecting everything except the NRF24 and see what happens?

I can't even get my NRF24's to work with the shop's listed boost with the Pro Mini attached without a 'massive' capacitor.

I tried to put a separate power supply.

General supply 5V 2 Amps.

I do not have the controller and I put two arduino nano for 3.3 volts

after 2 hours the system crashes.

if I put only one of the two radio system is fine.

I tried it with a standalone with two radio but without a monitor and the system works perfectly!!!

I have to put other capacitors?

Thank